Preheat oven to 400°.
Pour milk into a 9-inch pie plate; cover with foil. Place pie plate in a shallow roasting pan. Add hot water to pan to a depth of halfway up the sides of pie plate. Bake milk at 400° for 1 1/2 hours, adding additional water as needed. Remove pie plate from water. Uncover; stir milk with a whisk until smooth. Cool.
Place a large bowl in freezer. Let ice cream stand at room temperature 45 minutes or until softened.
With a rubber spatula or stand mixer, combine softened ice cream and milk in chilled bowl. Cover and freeze to desired consistency.